Advances and Limitations of Evidence-Based Medicine – Impact for Probiotics

the results of included trials to produce a single estimate of the effect of a particular intervention (i.e., a number or a graph) [1] . There are 2 major reasons why a metaanalysis is performed within a systematic review. The first is to increase the power, i.e. the chance to reliably detect a clinically important difference if one actually exists. The problem with many individual studies is that they are too small to detect little effects, which can only be observed if the data from several trials are combined. The second reason is to improve precision in estimating effects, i.e. narrow the confidence interval around the effect [1] .